Well...difficult to be sure without having precise measurements but I don't think you're too far off the mark Nice example and almost undamaged considering it's been fired ! Could be a base fuse round I suppose......so you did the right thing leaving it behind.
By the way, those parts you found from a Sherman track are superb !
Base fuse I agree still wouldnt like in my backpack.
Yes, until I learn a LOT more about ordinance, I'll remain SUPER cautious. When I was a sprout, a neighbour's dad blew his stomach out trying to defuse a practice bomb in his shop.
Looks like a 37mm M3 gun AP projectile: 37MM AP PROJECTILE, M-74, M-16 CASE
Long body; 'dual' driving band, the forward half shorter than the rear; groove near the base- all fit. The one shown is solid shot though it seems- no threads I can see, so the hollow must be for a tracer. According to the Wikipedia listing, there was only solid shot- no APHE. Still probably best to leave it be though...
Ohhhhh- pillage then burn...
I've got one of these somewhere, the hollow at the bottom is a tracer pocket, if you can put a pencil in the back end about 3/4" or so then its burnt off and depleted.
Those are a solid shot. The hole in the base is just for tracer element. Nothing unscrews from anything. That's why it's in such good shape. It's solid. As was pointed out, you're probably real close with ID but without measuring you can't be sure. I just layed mine out like you did and the scale looks the same. The Staghound has a .37 and I think the Matilda Tank used them too. Very widely used.